The present invention generally relates to laparoscopic surgical devices and methods and, in particular, insufflation gas humidifiers and warmers and methods thereof.
Less invasive procedures have been developed for conducting abdominal surgeries through tubular access devices commonly referred to as trocars. These procedures, which call for the placement of the trocar across the abdominal muscle, which defines the abdominal wall, are commonly referred to as laparoscopic procedures. Less invasive laparoscopic surgeries significantly reduce trauma and healing times resulting from the small puncture wounds associated with the trocars, as opposed to the large incisions associated with open surgery.
Laparoscopic procedures or surgeries, however, can be difficult to perform since the abdominal cavity is maintained substantially intact. This decreases visibility of the operative site and also provides a limited volume within which to manipulate instruments. In order to increase this volume as much as possible, the abdominal cavity is typically inflated or insufflated with carbon dioxide or other gas in order to distend the abdominal wall and increase the volume of the abdominal cavity. This insufflation takes place prior to, as well as during, the laparoscopic surgical procedure. Throughout this entire period, the insufflation gas is introduced to the cavity in order initially to distend the abdominal wall and ultimately to replace any escaping gas. The insufflation gas, e.g., carbon dioxide, is typically stored in cylinders under high pressure and released through regulators and valves. As the carbon dioxide expands, it cools and may reach water-freezing temperatures. The expanding gas is also extremely dry, i.e., almost no moisture content.
Introducing cold and dry gas into the abdominal cavity can be problematic. The insufflation gas will reach equilibrium with the surrounding abdominal cavity after it has reached body temperature and 100% relative humidity. The energy to heat cold and dry gas will come from the patient, which may be a significant amount of energy due to the latent heat of vaporization, which is 580 calories per gram of water at 37° C. Over the course of a lengthy surgical procedure 200 liters or more of gas may be used. The peritoneal lining of the abdominal cavity is highly vascularized and secretes a water-based lubricant that acts to protect organs as they slide against each other during normal function. This lining coats the entire abdominal cavity and has a surface area roughly equivalent to the surface area of the patient's skin. Application of cold and dry gas during laparoscopic surgery will severely dehydrate and cool the peritoneal layer and may contribute to post-operative pain and delayed or impaired healing. Additionally, the dry gas may remove the protective moisture of the sensitive abdominal structures, which may cause ileus, adhesions and other problems. Furthermore, the Laparoscopic patient is under anesthetic and lying on a stainless steel table and may therefore be vulnerable to hypothermia due to the aforementioned energy expenditure and/or the introduction of cold gas causing the core temperature of the patient to drop.
Previous attempts to provide solutions included heating insufflation gas at the insufflator. However, a warm gas loses its warmth during passage through the insufflation tubing. The carbon dioxide will be at ambient room temperature after traveling only a few feet through the insufflation tubing. As such, heating the carbon dioxide at the insufflator is ineffective. (See, for example, exemplary test results shown in FIG. 1). Insulated insufflation tubing also shows no appreciable improvement to the distance the carbon dioxide can travel prior to reaching ambient temperature. It becomes apparent that in such cases the carbon dioxide will arrive at the patient at room temperature.
In addition, any device that heats and humidifies the carbon dioxide should also be cost effective. Typical heaters at the insufflators or insulated insufflation tubing are costly or bulky. Such complications do not justify greatly increased expenditures to achieve warm and humid carbon dioxide.